By Media Coulibaly and Tim Cocks ABIDJAN, March 8 (Reuters) - Thousands of women marched through Abidjan on Tuesday calling for Laurent Gbagbo to step down, but witnesses said security forces shot four people dead near the scene of one and another was broken up by armed youths.

Gunfire erupted in several other places where protests had taken place through the afternoon.

Meanwhile, the United Nations said some 450,000 people are now believed to have fled their homes as a result of the post-election crisis, which African leaders will discuss again on Wednesday at the African Union headquarters in Ethiopia.

Demonstrations were held in various parts of Ivory Coast&${esc.hash}39;s main city, a week after Gbagbo&${esc.hash}39;s forces shot dead seven women at an all-female march in Abobo, a neighbourhood that has backed Alassane Ouattara, Gbagbo&${esc.hash}39;s rival.

Ivory Coast is the world&${esc.hash}39;s top cocoa producer and fears that violence will interrupt supplies have pushed cocoa futures to 32-year highs <CCc2>. Cocoa exports have stopped because of European Union sanctions. Gbagbo officials announced a plan to nationalise the cocoa industry on Monday, raising fears he may seize their stocks [ID:nLDE72718Y].

Ever since Gbagbo rejected U.N.-certified results showing he lost a November presidential election to Ouattara, supporters of the latter have seen their attempts at protest met with violent repression.

These ones initially appeared to go more peacefully, but were swiftly followed by outbreaks of gunfire.

In the downtown retail district of Treichville, witnesses said security forces fired on pro-Ouattara youths near a church, killing three young men and a 21-year-old women.

"It was a sit in. We prayed, some Muslims some Christians, then we went to St Jean church. Then we heard firing outside," said Helene Sommet, a Ouattara activist who helped evacuate the dead from the scene and take the wounded to a clinic.

"We took in 14 wounded. I&${esc.hash}39;m at the clinic right now," she said by telephone, adding that she saw a truck with some of Gbagbo&${esc.hash}39;s elite Republican Security Company in the street.

There was no immediate comment from Gbagbo&${esc.hash}39;s military.

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In Port Bouet, near Abidjan&${esc.hash}39;s airport, witnesses said about 50 pro-Gbagbo youths armed with AK47 assault rifles and machetes turned up to disperse 200 women who tried to march there.

"They fired into the air to disperse the women. They had weapons to intimidate them, but they didn&${esc.hash}39;t hurt anyone," said Bernard Aurega, a Ouattara party member who saw the march.

The election was meant to end a decade of instability and economic stagnation but resulted in deadlock and rising violence in Abidjan and the west of Ivory Coast has raised the prospects of another civil war.

The U.N. has said at least 365 people have been killed during the crisis. Diplomats think the real toll is much higher.

U.N. aid agencies have revised the figure for people displaced to about 450,000, including some 90,000 who have fled into neighbouring Liberia. [ID:nLDE7271O6]

Ouattara&${esc.hash}39;s camp said he is due to attend a meeting at the AU headquarters in Ethiopia this week to discuss the crisis but pro-Gbagbo officials said he would send representatives.

Optimism for a diplomatic breakthrough is low.

MARCHES, GUNFIRE, CLASHES

Security is deteriorating after gun battles between rivals in Abidjan and renewed hostilies in the west, where rebels controlling half the country since a 2002-3 war seized the town of Toulepleu from the government, the third in two weeks.

Gbagbos military and an allied militia group said they had taken it back on Tuesday, but the New Forces rebels denied it.

Seven women were killed last Thursday after security forces opened fire on protesters in the pro-Ouattara Abobo suburb.

Pro-Ouattara youths with AK-47s watched over them. But as soon as the march petered out, heavy machinegun fire erupted.

"It sounds like two groups fighting each other but I don&${esc.hash}39;t know," said resident Tiemoko Souala. Another said he saw Gbagbo&${esc.hash}39;s security forces move along the main street beforehand.

Abobo is now largely controlled by pro-Ouattara insurgents calling themselves the "invisible commandos", after a week of gun battles in which they pushed out police and military.

Western powers have warned Gbagbo he may face criminal investigation for crushing protests, although his military argues it has to, as protesters are often armed and violent.

Dozens were killed during an attempted march on Dec. 16, U.N. officials say, a protest followed by a wave of crackdowns on opposition areas in which scores were killed and kidnapped. (Additional reporting by Loucoumane Coulibaly; Writing by Tim Cocks; Editing by David Lewis and Matthew Jones)

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